首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   19218篇
  免费   1746篇
公路运输   5773篇
综合类   5361篇
水路运输   3793篇
铁路运输   5163篇
综合运输   874篇
  2025年   232篇
  2024年   611篇
  2023年   453篇
  2022年   590篇
  2021年   930篇
  2020年   884篇
  2019年   543篇
  2018年   463篇
  2017年   488篇
  2016年   469篇
  2015年   622篇
  2014年   1405篇
  2013年   1068篇
  2012年   1586篇
  2011年   1584篇
  2010年   1277篇
  2009年   1150篇
  2008年   1183篇
  2007年   1517篇
  2006年   1345篇
  2005年   785篇
  2004年   494篇
  2003年   313篇
  2002年   227篇
  2001年   203篇
  2000年   139篇
  1999年   76篇
  1998年   47篇
  1997年   37篇
  1996年   45篇
  1995年   37篇
  1994年   29篇
  1993年   25篇
  1992年   18篇
  1991年   21篇
  1990年   12篇
  1989年   16篇
  1988年   7篇
  1987年   3篇
  1986年   8篇
  1985年   10篇
  1984年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
601.
为适应钢材货源结构的变化,提高钢材货装卸质量,秦皇岛港对钢材装卸工艺及工属具进行改进和优化。分别介绍了钢板、铜板、型钢、盘条和卷钢装卸改进后的工艺,并将新旧装卸工艺作了比较,可供同行借鉴。  相似文献   
602.
对路面铣刨刀具结构组成、切削时象、工作状态和失效机理的进行了简洁的论述。着重分析了刀具正常失效和非正常失效产生的原因.提出了保证刀具正常失效的措施。  相似文献   
603.
Three weather sensitive models are used to explore the relationship between weather and home-based work trips within the City of Toronto, focusing on active modes of transportation. The data are restricted to non-captive commuters who have the option of selecting among five basic modes of auto driver, auto passenger, transit, bike and walk. Daily trip rates in various weather conditions are assessed. Overall, the results confirm that impact of weather on active modes of transportation is significant enough to deserve attention at the research, data collection and planning levels.  相似文献   
604.
杨小燕  盛利 《中国铁路》2021,(2):128-134
针对目前计划内接触网停电时电力机车进入无电单元(区)的问题,提出了基于动态停电作业区域数据对比库语音、屏幕鼠标点击坐标和高清成像分析进行"三元素二阶段"处理对比方法,以减少人员操作失误和损失.机车/车次信息及对应机车属性先由操作人员办理接发列预告(办理闭塞)的语音识别获取,再通过TDCS/CTC终端机非上位机获取并核对...  相似文献   
605.
高职专业设置中存在许多体制内外的问题,阻碍着高职教育的内涵型发展和科学发展。文中从高职教育认识误区、专业设置主体不清晰、专业设置管理内容不健全等三个方面,对高职专业设置中存在的教育体制机制缺陷产生的原因进行分析,旨在为高职专业设置管理体制机制改革提供科学依据。  相似文献   
606.
以4座主跨超过400 m的钢箱梁斜拉桥中跨合龙控制为背景,对大跨度钢箱梁斜拉桥中跨合龙的2种方法进行对比分析,对合龙各主要工序的关键技术进行研究。提出了合龙段配切长度的计算公式和合龙口宽度连续观测的测点布置方式。建议:在调整好合龙口姿态后可不加压重,也可不采用临时劲性骨架锁定;采用无线采集设备采集合龙口结构的温度场,用激光测距仪测量合龙口宽度以提高观测效率和安全性;在悬臂施工阶段关注梁长累计误差并通过调整后续梁段的制造长度消除之。  相似文献   
607.
《铁道工程学报》2021,(2):19-22and29
Research purposes: The micro-pile has been used in foundation replacement, building reinforcement, retaining soil reinforcement, but the design and calculation theory of the micro-pile is seriously lagging behind. The design and calculation method and content of the micro-pile are not clear, and there are no relevant regulations. In this paper, the design and calculation method of landslide treatment by micro-pile is discussed, and its effect is monitored and analyzed. Research conclusions: (1) There are many advantages such as flexible construction and high construction efficiency. For landslide project with limited terrain, micro-pile has good governance effect and adaptability. (2) The monitoring data show that it is appropriate to adopt micro-pile treatment in the landslide project. After the micro-pile reinforcement treatment, the deformation of the landslide project has been quickly and effectively controlled, and the safety of the tunnel and roadbed engineering has been guaranteed. (3) The design content of the micro-pile should include the overall stability, the length of the pile, the pile spacing, and the reinforcement of the pile. (4) This paper can provide guidance for the design and construction of using micro-piles to control railway landslide. © 2021, Editorial Department of Journal of Railway Engineering Society. All right reserved.  相似文献   
608.
基于Matlab/Guide的中小型电动船舶船机桨匹配设计研究   总被引:1,自引:1,他引:1  
在新船设计中,为了确定主机的功率、螺旋桨的最佳要素及正确的预报航速,使得船机桨达到良好的匹配,就需要对新船进行船机桨匹配设计。而传统的船机桨匹配设计主要是利用图谱法,但图谱法设计工作量较大,而且涉及到大量的图表和计算公式,因此影响计算结果精度。利用Matlab/Guide进行船机桨匹配设计、计算与分析的研究,使得在新船的船机桨匹配设计中,能够降低工作强度并提高设计结果的精度,让设计计算工作更加方便。  相似文献   
609.
Sales tax measures passed at the local level and dedicated to transportation projects have become increasingly popular in the United States. While revenues from fuel taxes stagnate, growth of local transportation sales taxes (LTSTs), most approved in local elections, has led to a gradual shift of the financial base for transportation projects away from user fees and toward broader-based taxes. In this study, the relationship between voter support and the social, political, and geographic characteristics of the voters is explored. Using precinct-level voting data and census demographic data for three local transportation sales tax elections in Sonoma County, in the San Francisco Metropolitan area of California, regression models were constructed to analyze this relationship. In addition, the relationship between the outcomes of the three measures was explored to better understand which transportation projects might have garnered more support for the successful measure. It was found that the closer voters lived to the transportation projects to be funded, the greater their support. Higher incomes were also positively related to support, controlling for other variables. Political leanings were found to affect support, with the direction of the effect dependent upon the project list in each measure’s expenditure plan. Finally, it appears that the latest measure, which passed successfully, benefited greatly from its multi-modal expenditure plan.  相似文献   
610.
文章介绍了横滩整治工程的措施与效果,分析该滩获得成功整治的关键技术与经验,为类似工程提供参考。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号